What is the algorithm for placing a pacemaker?

Algorithm for Placing a Pacemaker

The selection of pacemaker type and mode should be based on the underlying cardiac conduction abnormality, with consideration of patient factors including comorbidities, anticipated activity level, and presence of atrial arrhythmias. 1

Step 1: Determine Indication for Pacing

Class I Indications (Definite Need for Pacing):

• Symptomatic bradycardia
• Symptomatic sinus node dysfunction (sick sinus syndrome)
• Complete AV block
• Symptomatic second-degree AV block

Class II Indications (May Benefit from Pacing):

• Asymptomatic second-degree AV block
• Bifascicular block with intermittent complete heart block

Class III Indications (Pacing Not Indicated):

• Asymptomatic first-degree AV block
• Asymptomatic bifascicular block without prior transient complete AV block
• Asymptomatic sinus bradycardia with RR interval <3 seconds and minimum heart rate >40 bpm 1

Step 2: Evaluate Patient Factors

• Assess cardiac conduction abnormality pattern
• Evaluate comorbidities (especially heart failure, coronary disease)
• Consider degree of left ventricular dysfunction
• Determine anticipated activity level
• Review current and anticipated drug therapy
• Assess presence of atrial arrhythmias (especially AF)
• Consider patient age and life expectancy 1

Step 3: Select Pacing Mode and Device Type

For Sinus Node Dysfunction:

• If normal AV conduction: Single-chamber atrial pacemaker (AAI/AAIR)
• If impaired AV conduction or risk of AV block: Dual-chamber pacemaker (DDD/DDDR)
• If chronic AF with slow ventricular response: Single-chamber ventricular pacemaker (VVI/VVIR) 1

For AV Block:

• If normal sinus node function and desire for AV synchrony: Dual-chamber pacemaker (DDD/DDDR)
• If chronic AF or persistent atrial arrhythmias: Single-chamber ventricular pacemaker (VVI/VVIR) 1

For Patients with LV Dysfunction:

• If LVEF ≤40% and anticipated frequent ventricular pacing: Consider biventricular pacing (CRT) 1

Step 4: Implantation Procedure

1. Obtain vascular access (typically subclavian or axillary vein)
2. Position lead(s) under fluoroscopic guidance:
   • Atrial lead: Right atrial appendage or lateral wall
   • Ventricular lead: Right ventricular apex or septum
   • For CRT: Additional LV lead via coronary sinus
3. Test lead parameters:
   • Capture threshold (<1.0V @ 0.4ms is ideal)
   • Sensing amplitude (>2mV for ventricular, >1.5mV for atrial)
   • Lead impedance (200-1000 ohms)
4. Create pocket and secure generator
5. Program initial settings with adequate safety margin (output at least twice threshold) [@5@]

Step 5: Initial Programming and Follow-up

• Program output at 1.5-2.0V @ 0.4ms (at least twice threshold)
• Set appropriate lower rate limit based on patient needs
• For dual-chamber devices, program AV delay to optimize hemodynamics
• Schedule follow-up: 1-2 months post-implant, then 3-6 months, then every 6-12 months 2

Important Considerations and Pitfalls

• Minimize ventricular pacing in patients with preserved LV function to prevent pacing-induced cardiomyopathy
• Consider alternative RV pacing sites (septum, outflow tract) instead of RV apex in patients requiring frequent pacing
• Use rate-responsive features in patients with chronotropic incompetence
• Consider advanced algorithms that minimize ventricular pacing in dual-chamber devices
• Pacemaker implantation should be performed by individuals with appropriate training who maintain their skills through regular procedures 1

The selection between single-chamber and dual-chamber pacing remains an important clinical decision. While dual-chamber pacing provides AV synchrony, which is physiologically beneficial, single-chamber ventricular pacing may be appropriate in certain situations like chronic AF. For patients with LV dysfunction who require frequent ventricular pacing, biventricular pacing should be strongly considered to prevent further deterioration of cardiac function 1.